King, in chess, and in cards
Kicker, in American football
Strikeout, in baseball; a backwards K indicates someone striking out without swinging at the third strike
Kids, as in the acronym DINK, which means Dual Income - No Kids
Kindergarten, as in grades K-12
Kellogg's, the breakfast cereal maker, on the New York Stock Exchange
Potassium, the element, from the New Latin kalium, atomic number 19
Kilo, as in kilogram
Kilobyte, 1024 bytes
Thousand, as in 20K, for 20 thousand
Kelvin, the temperature scale. Zero degrees K is absolute zero, -273.15 degrees Celsius or −459.67°F
Killed, in genealogy

Other definitions not on the list:
Carat or karat, a unit of purity for gold alloys
Kings, Biblical books

But the one I know, but have difficulty with, is that K means OK in Internet chat. Okay, which I wrote about recently, is already a shortened form. This seems silly.

But it's NOT silly to KICK in and participate in ABC Wednesday this week. The KINDLY KREW will surely visit you.
***

Kourse you have to invent words beginning with "K" in English. There are in my English dictionary 7 1/2 pages of words starting with "K", whereas my Dutch dictionary has 57 pages of words beginning with "K".So "K"is always a difficult letter for us.Fantastic introduction!